Gaseous cold cathode indicator glow tube



Aug. 20, 1963 J, H. MOCAULEY ETAL 3,101,427

GASEOUS COLD CATHODE INDICATOR GLOW TUBE Original Filed Oct. 5, 1958 2 G2 4 INVENTOR.

JOHN H. MCC'AULEY F1 4 I BY STEVEN GAVURN/K MGM A TTORNE) United StatesPatent GASEQUS COLD CATHODE INDICATGR GLOW TUBE .l'ohu H. McQauley,Elizabeth, and Steven Gavurnik, Gladstone, NJ assignors to BurroughsCorporation, Detroit, Mich, a corporation of Michigan Continuation ofapplication Ser. No. 765,147, Oct. 3, 1958. This application May 18,196i Ser. No. 30,712

Claims. (Cl. 313-188) This invention relates to gaseous, cold cathodeglow tubes and particularlly to an improved and ruggedized mechanicalconstruction therefor.

This application is a continuation of application Serial No. 765,147,filed October 3, 1958, now abandoned.

One type of gaseous glow tube to which the principles of the inventionapply comprises a transparent envelope which contains an anode electrodeand one or more cathode glow indicator electrodes which are aligned in astack. The electrodes are mounted on support rods and are electricallyconnected to contact pins, the support rods and the contact pins beingsealed in the stem of the envelope. Tubes of this type are made in manydifferent sizes; and in all of these sizes, there are many small,delicate parts which are comparatively critically oriented with respectto each other. Up to the present time, a problem has existed as to howto assemble the various tube parts in the desired relationship while, atthe same time, obtaining a mechanically rugged construction.

Thus, the objects of this invention are to provide an improved coldcathode glow tube construction which is mechanically strong and ruggedand provides optimum use of tube parts for fulfilling both electricaland mechanical functions.

The principles of the invention are embodied in a gaseous glow tubewhich includes an envelope and a stem which supports the electrodeassembly within the tube. The electrode assembly includes, among otherthings, a plurality of cathode indicator glow electrodes mounted on, andsupported by, a plurality of thin wire support rods. According to theinvention, an auxiliary rugged support arrangement is provided in thearea of connection between the wire support rods and the electrodeassembly. The auxiliary support arrangement comprises an assembly of aplurality of insulating disks which are rigidly secured together as aunitary assembly by means of strong metallic inserts mounted in alignedapertures in the disks. Other similar inserts are provided which securetogether the insulating disks and various electrodes of the electrodeassembly. Some of the auxiliary inserts are also secured to the stemsupport rods by which the electrode assembly is secured to the stem.Thus, in this construction, the insulating disks are securely bound toeach other, to the electrode assembly, and to the tube stem.

The invention is described in greater detail by reference to thedrawings wherein:

FIG. 1 is a perspective view, partly in section, of a gaseous, coldcathode indicator glow tube embodying the invention;

FIG. 2 is an exploded view of the tube of FIG. 1;

FIG. 3 is a perspective view, partly in section, of a portion of thetube of FIG. 1; and

FIG. 4 is a perspective View, partly in section, of another portion ofthe tube of FIG. 1.

Referring to the drawings, a typical gaseous cold cathode indicator glowtube it} embodying the invention includes an envelope 12 which has beenevacuated and filled with a gas such as neon or the like at a suitablepressure to support cathode glow, e.g. about 50 to about 100 mm. of Hg.The envelope includes a base por- Bid-1,42? Patented Aug. 20, 1963 tion,or stem 14, through the periphery of which metal contact pins or lead-inwires 16 extend and by means of which electrical connection is made tosuitable external electrical circuit elements. The contact pins arepositioned on a common circumference on the stem 14. Within theenvelope, the contact pins 16 support the tube electrode assembly. Theenvelope 12 also includes a transparent viewing window 20 through whichglowing indicator cathode electrodes 22 are viewed. A sealedoif exhausttubulation (not shown) is provided in the stem 14.

According to the invention, an improved supporting structure for thetube electrodes is provided. This supporting structure comprises aunitary assembly of a plurality of disks of insulating material such asmica, ceramic, or the like. The assembly shown includes two disks 24 and26. However, more than two disks may be employed, if desired. In thetwo-disk assembly, the bottom mica disk 24 referring to the explodedview in FIG. 2 includes a central aperture 28 and a plurality ofperipheral apertures 3h spaced apart on a common circumference near theperiphery of the disk. The apertures 30 are aligned with the pins 16 inthe assembled tube. The top mica disk '26 includes a central aperture32, two diametricaly opposed peripheral apertures 34, and at least oneother peripheral aperture 36. The central aperture 32 in the disk 26 isaxially aligned with the central aperature 28 in the disk 24, and,similarly, the apertures 34 and 36 in disk 26 are aligned withcorresponding apertures 3t in disk 24 when the disks 24 and 26 areassembled and are in contact with each other.

Means are provided for strengthening and reinforcing the assembly ofmica disks. Referring to the bottom mica disk 24 (FIGS. 2 and 3), thismeans comprises a tubular sleeve or eyelet 38 positioned in each of aplurality of the peripheral apertures 30. The sleeves 3i;

serve to strengthen and rigidify the assembly and may be employed in asmany of the apertures 30 as desired. It is preferable to provide atleast three sleeves 33 oriented at the apices of an imaginary trianglein the plane of the disk 24. The lower end of each sleeve extends belowthe bottom mica disk 24, and a lip or flange 4h at the upper end of eachsleeve is seated on the top surface of the disk 24. The top and bottommica disks (FIG. 3) are secured together, with their correspondingapertures aligned, by means of a sleeve or rivet 42 which is inserted inthe aligned central apertures 28 and 32 and which includes flanges ateach end which bear against the mica disks. Thus, the sleeve 42 servesto'hold the two mica disks securely and rigidly together as a unitaryassembly 43. Since the mica disks 24 and 26 are secured together byother means, as described below, the sleeve 42, although desirable, isnot required.

The supporting structure also includes the anode electrode of the tubewhich comprises a generally cupshaped metallic electrode 44 having aflat base 46 and a generally cylindrical side wall 43. The anode cupelectrode 44 is seated on the mica disk assembly 43, with its base incontact with the top surface of the top mica disk. The base of the cupelectrode is provided with two diametrically opposed peripheralapertures 50 which are aligned with the corresponding diametricallyopposed peripheral apertures in the two mica disks 24 and 26. The baseof the cup is also provided with at least one other peripheral aperture52 aligned with corresponding apertures in the disks.

A tubular sleeve 54 is provided in each of the sets of diametricallyopposed peripheral apertures in the two mica disks 24 and 26 and in thebase 46 of the cup electrode. These sleeves include upper flanges 56which bear against the top surface of the base of the cup and lowerflanges 57 which bear against the bottom surface of the bottom mica 24-and thus hold the mica disks and cup electrode in a unitary, rigid andstrong assembly. All of the tubular sleeves are preferably made of ametal and are of rugged and strong construction to provide the desiredstrength in the support assembly. The two diametrically opposed sleeves54 are preferably stronger than the other sleeves and are made ofheavier gauge material since these sleeves support more weight than theothers.

The cup-shaped electrode 44 is also preferably of metal and is providedin its cylindrical wall with a pair of diametrically opposed slots 58and 60, positioned adjacent to the diametrically opposed sleeves 54.These slots allow leads to be connected between the cathode electrodesand the contact pins in a manner to be described. The wall of the cupmay be provided with a plurality of tabs 61 which extend outwardlytherefrom and bear against the envelope. The tabs thus assist incentering and supporting the electrode assembly.

The support assembly is secured to the stem by introducing each pin 16into the lower open end of one of the peripheral sleeves 38 (FIG. 1)with which it is aligned. The sleeves are then crimped or welded to thepins. Thus, the pins 16 rigidly support the assembly of mica disks andanode cup. Under some circumstances, the electrical requirements of thetube 10 may be such that one or more pins 16 cannot be connected toreinforcing sleeves. However, adequate strength is still maintained. Thediametrically opposed sleeves 54- may also be coupled to pins 16.However, it is more convenient to reserve them for another purpose to bedescribed. A metal tab 62 is also connected between the cup 44 throughthe apertures 52, 36, and 30 and a sleeve 38 to one of the pins 16.Electrical connection to the anode cup is thus provided.

The diametrically opposed sleeves 54 are used as follows. A pair ofsupport posts '64 and 66 are inserted in the sleeves 54 and are securedthereto by crimping or welding or the like. The support posts 64 and 66extend vertically above the base of the cup 44 adjacent to the slots 58and 60-. The posts 64 and 66 are provided with an insulating coating orsleeve of a material such as ceramic, glass, or the like (not shown).

The electrode assembly in the tube 10 includes indicator cathodeelectrodes 68 which may take substantially any desired shape; forexample, they may be numbers, letters, or the like, and they may be asfew in number as desired, or as many as is practical for the size of thetube. Such cathodes are comparatively fragile and have small unitsurface areas. In one form of the tube 10 wherein the cathode elementsare numbers, ten of such elements are provided, including the numbers to9. Fewer than ten cathodes are shown in FIG. 1 for purposes ofsimplification of the drawing. The cathode elements 68 are made of anysuitable metal, for example, stainless steel, aluminum, Nichrome,molybdenum, or the like, and they may be made in any suitable fashion,for example, by etching, stamping, or the like.

The cathode elements68 are provided with diametrically'opposed aperturcdend tabs 70, by means of which they are mounted and supported on thesupport posts 64 and 66. The cathode elements are stacked on the posts64 and 66, one above the otherwith their surfaces oriented parallel toeach other transverse to the vertical axis of the tube and facing theviewing window 20 of the envelope 12. The cathode elements are suitablyinsulated from each other, for example, by means of insulating spacers72 threaded on the posts 64' and 66 between them, the spacers beinglarger than the tabs and having sufficient surface area to cover andinsulate the cathode tabs to prevent the tabs from glowing. The stack ofelectrodes is locked on the posts 64 and 66 by any suitable means, forexample sleeves 74.

Each cathode indicator electrode 68 is provided with a fine wireconnecting lead 76 which may be or the same material as the numbers orthey may be of any other suitable material. The lead of each cathodeextends through one of the slots 53 or 60 in the cup 44 and is securedbeneath the cup to one of the pins 16. For convenience, only two suchleads and connections are shown in FIGS. 1 and 2.

An auxiliary electrode is provided in the tube 10 to prevent sputteringof cathode material onto the viewing window. This electrode may also beused as part of the anode of the tube along with the cup electrode 44.This auxiliary electrode comprises a comparatively fine mesh screen 78mounted at the top of the stack of glow cathodes 68. The screen 78 isinsulated from the adjacent cathode by washers or spacers 72, just asthe cathodes are insulated from each other. When used as part of theanode assembly, the screen 78 is electrically connected to the cup bymeans of one or more metal tabs 80 secured between the edge of thescreen 78 and the cylindrical wall of the cup. This connection also addsstrength and rigidity to the entire electrode assembly. It may bedesirable to coat the anode lead and pin with a layer (not shown) of asuitable insulating material, such as aluminum oxide, 21 glass frit, orthe like, to insulate them from the other leads and pins and to preventthem from glowing during operation of the tube.

In preparing the tube 10, several sub-assemblies may be prepared beforethe entire tube is assembled. One sub-assembly may comprise the stem 14and the contact pins 16 sealed therein. A second sub-assembly maycomprise the insulating disks 2:4 and 26 carrying the various sleevesand having the cup 44 and support posts 64 and 66 secured thereto. Thissecond sub-assembly is strong and rugged because of the manner in whichthe insulating disks are secured together and because of the manner inwhich the cup and support posts are secured to the disks. After thesecond sub-assembly has been prepared, the electrode assembly is mountedthereon, and then the entire assembly is secured to the contact pins inthe stem. Finally, the envelope is sealed to the stem and the tube isprocessed to completion.

The principles of the invention are illustrated in the foregoingdescription of an improved and rugged construction for a multi-cathodeindicator glow tube. It will be clear to those skilled in the art thatmany modifications may be made in the specific features set forth abovewithin the spirit of the invention. For example, the electrode supportassembly comprising a plurality of insulating 'disks may include morethan tWo of such disks, if desired. In addition, any number ofstrengthening sleeves may be provided so long as the necessary electrical relationships between the various portions of the tube aremaintained.

What is claimed is:

l. A gaseous cold cathode indicator glow tube including an envelopefilled with a gas at a pressure to sustain cathode glow, a stem at oneportion of said envelope including a plurality of electricallyconductive pins extending therethrough, a pair of spaced-apart supportposts within said envelope, a viewing window at another portion of saidenvelope, a stack of cathode glow electrodes mounted on said pair ofspaced-apart support posts and facing said viewing window, said cathodeelectrodes being in the form of indicator characters orientedsubstantially parallel to each other and insulated from each other insaid stack, a cup-shaped anode electrode in said envelope saidcup-shaped anode having an apertured side wall, a lead extending fromeach cathode through the apertured wall of said anode along the lengthof the cup and the stack of cathode electrodes to one of said conductivepins, and including a plate portion positioned at the bottom of saidstack of cathode electrodes, means securing said support posts to saidplate portion of said anode, and a support assembly for said electrodes,said support assembly comprising a plurality of insulating disks securedtogether by reinforcing members coupled to a plu- 2. The tube defined inclaim 1 wherein said support assembly comprises a sandwich of aplurality of insulating disks, the disks having a plurality of alignedapertures, each group of apertures thus formed being aligned with one ofsaid conductive pins, a plurality of reinforcing members present in someof said groups of apertures and securing said disks together in a strongand rigid unitary assembly, a plurality of said reinforcing membersbeing secured to selected ones of said conductive pins, saidspaced-apart support posts being secured to others of said reinforcingmembers.

3. A gaseous cold cathode indicator glow tube including an envelopefilled with a gas at a pressure to sustain cathode glow, a stem at oneportion of said envelope including a plurality of electricallyconductive pins extending therethrough, a pair of spaced-apart supportposts in said envelope, a viewing window at another portion of saidenvelope, a stack of cathode glow electrodes mounted on said pair ofspaced-apart support posts and facing said viewing window, said cathodeelectrodes being in the form of indicator characters orientedsubstantially parallel to each other and insulated from each other, agenerally cup-shaped anode electrode in said envelope, electrical leadsextending from said cathodes outside said anode to said pins and asupport assembly for said electrodes, said support assembly comprising aplurality of insulating disks, a plurality of reinforcing fastenerssecuring said disks together and coupled to a plurality of saidconductive pins in said stem, said cup-shaped anode being secured tosaid insulating disks, said stack of cathode electrodes being mountedsubstantially inside said cup anode.

4. The tube defined in claim 3 and including an auxiliary electrodemounted at the top of said stack of electrodes and insulated therefrom,said auxiliary electrode being secured to said cup anode.

5. The tube defined in claim S'Wherein said envelope includes a sidewall secured to said stem and including a plurality of spacer memberspositioned between said cup anode and the wall of said envelope.

6. A gaseous cold cathode indicator glow tube including an envelopefilled with a gas at a pressure to sustain cathode glow, a stem at oneportion of said envelope including a plurality of electricallyconductive pins extending therethrough, a pair of'spaced-apart supportposts in said envelope, a viewing window at another portion of saidenvelope, a stack of cathode glow electrodes mounted on said pair ofspaced-apart support posts and facing said viewing window, said cathodeelectrodes being in the form of indicator characters orientedsubstantially parallel to each other and insulated from each other, acup-shaped anode electrode insaid envelope, means securing said supportposts to said anode electrode, leads extending from said cathodesoutside said anode to said pins and a support assembly for saidelectrodes, said support assembly comprising a sandwich including bottomand top insulating disks, each of said disks having a plurality ofapertures, some of the apertures in each being aligned to provide groupsof apertures, the base of said cup anode being seated on the topinsulating disk and having a plurality of apertures aligned with alignedapertures in said disks, a plurality of reinforcing and fasteningmembers seated in separate apertures in'said bottom disk, a plurality ofreinforcing and fastening members seated in aligned apertures in boththe top and bottom disks, and other reinforcing and fastening membersseated in the base of said cup anode and said disks and securing saiddisks and anode together in a rigid unitary assembly, a plurality ofsaid reinforcing members being secured to separate conductive pins, saidsupport posts being secured to others of said reinforcing members.

said base of 65 7. A gaseous cold cathode indicator tube including anenvelope having a viewing window and filled with an ionizable gassuitable for supporting cathode glow, a stem comprising a portion ofsaid envelope and including a plurality of pins extending into saidenvelope, a cup-shaped anode member having a base and a slotted sidewall, a pair of apertures formed in said base of said cup-shaped memberand spaced apart a fixed distance, a tubular eyelet fixed in each ofsaid apertures in said base, a support post positioned in each of saideyelets and secured thereto, said support posts extending upwardly fromsaid base parallel to each other and spaced apart a fixed distance, aplurality of filamentary cathode electrodes mounted in a stack on saidsupport posts and spaced apart from each other, a cathode lead securedto each cathode and extending through the slotted side wall of saidcup-shaped member and along the length of the stack of cathodes to oneof said pins whereby external electrical connection may be made to eachof said cathodes, and means securing said cup-shaped member and theelectrodes carried thereby to said pins.

8. The tube defined in claim 7 where-in said last-named eans includes atleast one auxiliary eyelet secured to said cup-shaped member and to oneof said pins.

9. The tube defined in claim 7 wherein said last-named means includes aplurality of insulating plates secured together in a unitary consructionand secured as a unit to said cup-shaped member and fastening meanssecuring said insulating plates to selected ones of said pins andauxiliary fastening means securing said cup-shaped member to a pin.

10. An indicator tube including an envelope having a viewing window andfilled with a gas at glow discharge pressure,

a plurality of tube pins secured to said envelope,

a first insulating disk having a plurality of apertures,

generally hollow metallic inserts positioned in a plurality of saidapertures,

a second insulating disk secured to said first insulating disk having aplurality of apertures aligned with the apertures in said first disk,

a pair of electrode support posts secured to two of said inserts andspaced apart a fixed distance and extending away from the surface ofsaid second insulating disk,

a plurality of cathode glow electrodes facing saidviewing window andsupported on said posts insulated from and spaced apart from each otheralong the axis of the tube,

a generally cup-shaped anode having a base and an apertured side walland enclosing said cathode electrodes,

said cup-shaped anode having its base seated on said second insulatingdisk,

and a lead extending from each cathode through the apertured wall ofsaid cup-shaped anode and along the outside of the cup to a tube pin,

a plurality of said inserts being secured to a plurality of said tubepins whereby said cup-shaped anodeand said cathodes and said disks arerigidly and securely mounted within said envelope.

References Qited in the file of this patent UNITED STATES PATENTS2,632,128 Hancock Mar. 17, 1953 2,735,038 Hancock Feb. 14, 19562,833,949 Driscoll May 6, 1958 FOREIGN PATENTS 677,883 I Great BritainAug. 27, 1952

1. A GASEOUS COLD CATHODE INDICATOR GLOW TUBE INCLUDING AN ENVELOPEFILLED WITH A GAS AT A PRESSURE TO SUSTAIN CATHODE GLOW, A STEM AT ONEPORTION OF SAID ENVELOPE INCLUDING A PLURALITY OF ELECTRICALLYCONDUCTIVE PINS EXTENDING THERETHROUGH, A PAIR OF SPACED-APART SUPPORTPOSTS WITHIN SAID ENVELOPE, A VIEWING WINDOW AT ANOTHER PORTION OF SAIDENVELOPE, A STACK OF CATHODE GLOW ELECTRODES MOUNTED ON SAID PAIR OFSPACED-APART SUPPORT POSTS AND FACING SAID VIEWING WINDOW, SAID CATHODEELECTRODE BEING IN THE FORM OF INDICATOR CHARACTORS OREINTEDSUBSTANTIALLY PARALLEL TO EACH OTHER AND INSULATED FROM EACH OTHER INSAID STACK, A CUP-SHAPED ANODE ELECTRODE IN SAID ENVELOPE SAIDCUP-SHAPED ANODE HAVING AN APERTURED SIDE WALL, A LEAN EXTENDING FROMEACH CATHODE THROUGH THE APERTURED